1. Field of the Invention
This invention relates to devices for controlling the amount of X-ray irradiation in X-ray photographing for medical diagnosis, and in particular relates to X-ray photographing for dental diagnosis.
2. Prior Art
Generally, an X-ray photographing apparatus for stomatic use in dental treatment is placed under a restraint under which a photograph is taken by inserting a film into the mouth of a patient. Accordingly, the amount of X-ray irradiation is indirectly controlled by regulating the voltage and current of an X-ray tube and a period of time of irradiation. Accordingly, the result is that there is a tendency that fluctuation in the voltage and the like of the X-ray tubes cause variation in the amount of radiation. Accordingly, repetition of photographing due to too large or too small an amount of radiation exposure of the film exposes a patient to overdoses of X-rays and makes it difficult to take X-ray photographs of the same quality.